Experiments will be done to elucidate the structure of the ribosome of E. coli and to relate that structure to the function it plays. Radioactive EF-G will be prepared and crosslinked to the ribosome. Isolation of the EF-G containing complexes which result should allow identification of the ribosomal proteins in the EF-G binding site. Studies of this kind will be extended to include EF-Tu. Conventional monofunctional reagent blocking experiments will be undertaken with two goals in mind: (1) identification of the cause of the heterogeneous response of ribosomes to thiol blocking agents, (2) discovery of compounds which will specifically inactivate the ribosomal GTPase and the peptidyl transferase. This work should help clarify the significance of ribosomal heterogeneity and provide clues as to the mechanism of two of the ribosome's catalytic activities. An attempt will be made to crystallize the ribosome and/or its subunits with the hope of opening the way to a study of its structure at the atomic level.